This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Group II introns are one of the largest ribozymes (catalytic RNA molecules) in Nature and they catalyze a splicing reaction that is essential for production of processed RNA molecules in many organisms. This class of introns is of interest for two major reasons: The group II class of introns is believed to represent an evolutionary predecessor of the more complex eukaryotic spliceosmal machine, which is necessary for pre-mRNA processing in humans and other higher organisms. Group II introns are therefore believed to represent an important model for understanding the molecular mechanisms for messenger RNA production, which is a central process in human health and disease. A second reason they are important is that free group II introns are reactive, mobile genetic elements that can insert themselves into new genes and colonize new organisms. In this way, they have radically shaped the evolution of almost all terrestrial genomes. The group II intron insertion reaction is being explored as a promising tool for gene therapy and biotechnological innovation. At NE-CAT, we are collecting data on the molecular structure of group II introns, so we can understand how they catalyze splicing and mobility reactions. NE-CAT played a pivotal role in solving the first crystal structure of a group II self-splicing intron, which was published in April of 2008.